This invention relates to a rotary actuator and system. The invention is particularly suitable for use in aerospace applications, for example for use in moving the flaps, hatches or doors of an aircraft.
In a typical actuator system for a flap of an aircraft, for example one of the high lift leading edge flaps, a pair of rotary actuators are driven by a common drive shaft, the actuators being connected to respective levers or arms mounted adjacent opposite ends or edges of the flap. Where a plurality of flaps are to be moved in unison, the actuators associated with each flap may be driven by a common drive shaft. The provision of two rotary actuators associated with each flap results in the actuator system being heavy. It is an object of the invention to provide an actuator system of reduced weight It is a further object of the invention to provide an actuator suitable for use in such an actuator system which permits the detection of a fault indicative of a skew condition, and to provide a skew detection system suitable for use with other actuator systems.
According to a first aspect of the invention there is provided an actuator system comprising a rotary actuator having an input, a first output, and a second output, the first and second outputs being arranged to move at substantially the same angular speed upon rotation of the input, a drive shaft coupled to the input, and first and second output shafts coupled, respectively, to the first and second outputs.
The first and second output shafts may be coupled, in use, to respective arms or levers associated with opposite edges of a flap.
Such an actuator system is advantageous in that a single rotary actuator is associated with each flap. As a result, the actuator system is of reduced weight.
The first and second output shafts conveniently comprise torque tubes. The drive shaft conveniently extends through at least one of the torque tubes.
According to a second aspect of the invention there is provided a rotary actuator comprising an input, a drive member angularly moveable within a housing in response to rotation of the input, first and second angularly moveable outputs, and a drive arrangement for transmitting movement of the drive member to the first and second outputs.
The drive arrangement conveniently comprises a differential drive arrangement permitting limited relative angular movement of the first and second outputs. The differential drive arrangement conveniently comprises a xe2x80x9cdog bonexe2x80x9d differential drive arrangement.
Preferably, the rotary actuator further comprises a detection arrangement arranged to produce an output signal in the event that relative angular movement occurs between the first and second outputs.
The second output may include a member spring biased towards the drive member, the detector arrangement including a ball/ramp arrangement arranged to drive the said member of the second output against the action of the spring biasing in the event of relative angular movement occurring between the first and second outputs, and a position sensor arranged to monitor the position of the said member.
Where such an arrangement is used to move an aircraft flap, in the event of a skew condition arising, relative angular movement will occur between the first and second outputs, and as a result the said member will move, the movement being detected by the position sensor which generates a signal indicative of the presence of a skew condition.
In an alternative embodiment, one of the output shafts may carry an annular member, the detection arrangement including a C-spring arrangement arranged to act on the annular member. The drive member of the rotary actuator may be provided with at least one aperture for receiving a roller member, the roller member being engaged between the C-spring arrangement and the annular member. The C-spring arrangement may include a plurality of C-springs.
The detection arrangement may comprise at least one detent member received within a recess provided in the drive member and engaging a surface of the plate member, the detection arrangement being arranged such that, in the event of relative angular movement between the first and second outputs, relative movement between the annular member and the drive member causes the detent member to ride out of the recess, thereby causing movement of the plate member.
A position sensor may be employed to sense the position of the plate member. In the event of a skew condition arising, relative angular movement will occur between the first and second output, and as a result the plate member will move, the movement being detected by the position sensor which generates a signal indicative of the presence of a skew condition.
According to another aspect of the invention there is provided a detection arrangement for use with a rotary actuator as described herein, the detection arrangement comprising first and second angularly moveable members, a ball and ramp arrangement arranged such that, upon relative angular movement occurring between the first and second members, one of the first and second members moves axially, and a position sensor arranged to provide an output signal in the event that axial movement of the said one of the first and second members is detected.
According to another aspect of the invention, there is provided a detection arrangement for use with a rotary actuator as herein described, the detection arrangement comprising first and second angularly moveable members and a plate member arranged such that, upon relative angular movement occurring between the first and second members, the plate member is caused to move, a position sensor being arranged to provide an output signal in the event that movement of the plate member is detected.
In each case, the first and second members of the detection arrangement may be coupled to one another by a differential drive arrangement, for example a dog bone differential drive arrangement.